The first basic change presented in Listing 4 is the extension of the ACORD schema by adding an optional element for a party's social security number (SSN).

清单4中的第一种基本变化是ACORD模式的扩展，增加了一个可选元素表示参与者的社会安全号码(SSN)。

youdao

For us persons, this must be your Social Security Number (SSN) or Individual Taxpayer Identification Number (ITIN).

对于美国的人，这一定是您的社会安全号码(SSN)或个人的纳税人识别号码(ITIN)。

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You generally need a Social Security Number (SSN) to claim a dependent on your federal income tax return.

FORBES: Ask The Taxgirl: Social Security Numbers for Dependents